Thursday, September 24, 2009
Tahitian vanilla orchid
Rare Vanilla Had Roots in Maya Gardens, Genes Reveal
Vanilla is the No. 1 flavor for ice cream in the U.S., which consumes most of the world's vanilla supply. The spice is produced from the fruit, or "beans," of two orchid species, Vanilla tahitensis (in the photo) and Vanilla planifolia. Only about five percent of natural vanilla used in food comes from V. tahitensis, commonly known as Tahitian vanilla.
Scientists may have solved the mystery of the origin of the Tahitian vanilla orchid, the rare plant that produces a richly-flavored spice esteemed by vanilla gourmets.
The orchid is known to exist only in cultivated or feral stands, primarily on the French Polynesian island Tahiti. Natural, wild populations have never been found.
But now botanists think they know where it came from, and how it got to Tahiti hundreds of years ago.
A team of investigators led by Pesach Lubinsky, a postdoctoral researcher in the University of California Riverside's department of botany and plant sciences, set out its theory in the current issue of the American Journal of Botany.
Using genetic and ethnohistoric analysis, they argue that Vanilla tahitensis began its evolutionary journey as a pre-Columbian Maya cultivar inside the tropical forests of Guatemala.
"All the evidence points in the same direction," Lubinsky said. "Our DNA analysis corroborates what the historical sources say, namely, that vanilla was a trade item brought to Tahiti by French sailors in the mid-19th century.
"The French admiral responsible for introducing vanilla to Tahiti, Alphonse Hamelin, used vanilla cuttings from the Philippines. The historical record tells us that vanilla -- which isn't native to the Philippines -- was previously introduced to the region via the Manila galleon trade from the New World, and specifically from Guatemala."
The Manila galleons were Spanish trading ships that sailed once or twice each year between 1565 and 1815 across the Pacific Ocean between Manila in the Philippines and Acapulco, Mexico, according to a UC Riverside statement. The ships brought Chinese porcelain, silk, ivory, spices, and other exotic goods to Mexico in exchange for New World silver.
Genetic data confirmed that the closest relatives to Tahitian vanilla, from among 40 different vanilla species analyzed from across the world, were two species that grow naturally only in the tropical forests of Central America: Vanilla planifolia and Vanilla odorata.
V. planifolia is the primary species cultivated for commercial vanilla, and is grown principally in Madagascar and Indonesia. V. odorata has never been cultivated.
But a problem for Lubinsky and his colleagues was that no Tahitian vanilla could be found growing wild in Guatemala, which is where its two closest relatives grew.
A second look at the genetic data led to the discovery that Tahitian vanilla was in fact a hybrid offspring between V. planifolia and V. odorata.
Tahitian vanilla (V. tahitensis) flanked by its parents V. odorata (top) and V. planifolia
"That's where the Maya cultivators come in," Lubinsky said. "The pre-Columbian Maya had been managing their forests for millennia to cultivate cacao and to make chocolate, and we know they were also cultivating vanilla to use it as a chocolate spice.
"The Maya created these forest gardens by introducing different types of species of wild cacao and vanilla from the surrounding forests, which meant that species that had previously been geographically separated were then able to hybridize because they were in the same place.
"That's the scenario we present in our research paper for how Tahitian vanilla got started. It is an evolutionary product, but also a Maya artifact."
The discovery that vanilla species can exchange genes across species barriers provides an opportunity to breed new commercial varieties of vanilla through hybridization in the future, commented Seung-Chul Kim, an assistant professor of systematics in the department of botany and plant sciences and a coauthor on the research paper